Logo link to homepage

Report on Semeru (Indonesia) — August 2001

Bulletin of the Global Volcanism Network, vol. 26, no. 8 (August 2001)
Managing Editor: Richard Wunderman.

Semeru (Indonesia) Continuous seismic activity, plumes to ~11.6 km

Please cite this report as:

Global Volcanism Program, 2001. Report on Semeru (Indonesia) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 26:8. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200108-263300.

Volcano Profile |  Complete Bulletin


Semeru

Indonesia

8.108°S, 112.922°E; summit elev. 3657 m

All times are local (unless otherwise noted)


From August 2000 through August 2001, activity at Semeru was characterized by continuous seismic activity and ash-and-steam plumes of varying heights above the summit. The Alert Level at Semeru remained at level 2 (on a scale of 1-4) throughout the report period.

The Darwin Volcanic Ash Advisory Center (VAAC) reported volcanic ash plumes and clouds on several occasions throughout the year (table 5). The plumes ranged from ~4.6 to ~11.6 km altitude, and moved mainly SSE. On 8 July at 1503 a SE-drifting ash plume rose to ~2.5 km above the volcano. Ground-based reports prior to the eruption revealed that each day during 18-24 June Semeru emitted ash to ~0.6 km above the volcano.

Table 5. Summary of Volcanic Ash Advisories from the Darwin VAAC issued between August 2000 and August 2001. Note that heights are given in altitude. Semeru's summit lies at 3,767 m above sea level. Information sources include air reports (for example, routed via airlines, AIREPS), pilot reports (PIREPS), satellite data, and reports from ground observations), and information from the Meteorological and Geophysical Agency of Indonesia. Source date was provided by the Darwin VAAC.

Date Time Source Comment
19 Aug 2000 0653 PIREPS Possible smoke plume observed extending to ~10.6 km and moving S to SE.
19 Aug 2000 0812 PIREPS Possible smoke plume extending to ~4.6 km.
20 Aug 2000 0944 AIREP Smoke plume observed extending to ~7.3 km.
21 Aug 2000 0938 AIREP Smoke plume observed extending to ~7.3 km.
14 Sep 2000 1135 AIREP Stationary smoke plume at ~6 km.
10 Oct 2000 0333 AIREP Volcanic ash cloud at ~6 km and ascending.
10 Oct 2000 0433 AIREP Volcanic ash cloud at ~6 km and ascending.
10 Oct 2000 1030 AIREP Volcanic ash cloud at ~6 km and ascending.
11 Oct 2000 0216 AIREP Volcanic ash cloud at ~6 km and ascending.
11 Oct 2000 0435 AIREP Volcanic ash cloud at ~6 km, intermittent discharge extending to a maximum of 30 NM.
11 Oct 2000 0528 AIREP Volcanic ash cloud at ~6 km, intermittent discharge extending to a maximum of 30 NM.
11 Oct 2000 0925 AIREP Volcanic ash cloud at ~6 km, intermittent discharge extending to a maximum of 30 NM.
13 Oct 2000 0426 AIREP Volcanic ash cloud at ~6 to ~7.6 km drifting SW.
27 Oct 2000 0215 AIREP Volcanic ash cloud at ~7.6 km lasting for ~10 minutes.
30 Oct 2000 1055 AIREP Volcanic ash cloud at ~6 km.
11 Dec 2000 0508 AIREP Volcanic ash to ~7.6 km.
08 Jul 2001 0929 AIREP Ash plume reported to ~6 km drifting SE.
09 Jul 2001 0857 AIREP Ash plume to ~6 km drifting SE.
09 Jul 2001 2355 AIREP Volcanic ash at ~11.6 km.
09 Jul 2001 0857 AIREP Ash plume reported to ~6 km drifting SE.

Explosion earthquakes dominated the seismicity (table 6), and pyroclastic flows occurred 17 times between 31 July 2000 and 15 July 2001. The Volcanological Survey of Indonesia (VSI) reported that a significant change in seismic activity occurred during 3-9 October 2000, when the number of explosion earthquakes increased to more than 700. A pyroclastic flow that reached the Kembar Besuki river, as far as 2,500 m from the summit, occurred on 2 October.

Table 6. Summary of seismicity at Semeru, 31 July 2000-15 July 2001. Ash plume heights are distances above the summit unless otherwise noted. Courtesy of the Volcanic Survey of Indonesia (VSI).

Date Deep Volcanic (A-type) Shallow Volcanic (B-type) Explosion Avalanche Tectonic Comment
31 Jul-07 Aug 2000 4 5 657 64 22 Five pyroclastic flows. Five pyroclastic-flow earthquakes. Four tremor events.
08 Aug-14 Aug 2000 5 4 584 43 13 Two pyroclastic flows; ash plume ~600 m. Two tremor events.
15 Aug-21 Aug 2000 2 -- 420 17 5 Ash plume ~600 m.
22 Aug-29 Aug 2000 23 1 542 27 21 Ash plume ~600 m. Three pyroclastic-flow earthquakes.
29 Aug-04 Sep 2000 23 1 542 27 21 Ash cloud ~600 m. Three pyroclastic-flow earthquakes.
05 Sep-11 Sep 2000 -- 2 594 8 -- Ashfall (105 events); white cloud to ~700 m.
12 Sep-18 Sep 2000 -- -- 623 -- -- Three pyroclastic flows; ashfall (72 events); ash plume to ~600 m. Two tremor events.
19 Sep-25 Sep 2000 -- 3 556 98 16 Ash plume to ~600 m.
26 Sep-02 Oct 2000 2 2 582 19 1 Thin white ash plume. One pyroclastic-flow earthquake. 79 tremor events.
03 Oct-09 Oct 2000 1 1 707 80 14 One pyroclastic flow.
10 Oct-16 Oct 2000 1 3 592 41 13 One pyroclastic flow; ash plume to ~600 m.
17 Oct-23 Oct 2000 3 -- 607 25 -- --
24 Oct-30 Oct 2000 42 1 592 22 7 Volcano covered by haze. Four tremor events.
31 Oct-06 Nov 2000 16 1 561 48 13 Ash plume to ~600 m.
28 Nov-04 Dec 2000 8 -- 483 24 2 Thick white fume 600 m above Jonggring Seloko crater.
05 Dec-11 Dec 2000 1 1 513 16 6 Two pyroclastic flows; thick white fume 600 m above Jonggring Seloko crater.
12 Dec-18 Dec 2000 2 -- 598 38 5 Volcano covered by smog.
19 Dec-25 Dec 2000 -- 1 319 22 2 --
26 Dec-01 Jan 2001 1 -- 559 98 7 White-gray ash plume to 600 m.
02 Jan-08 Jan 2001 6 -- 579 80 10 --
09 Feb-15 Feb 2001 29 1 693 80 4 --
13 Feb-19 Feb 2001 1 -- 519 29 1 No visual observations because of cloudy weather.
20 Feb-26 Feb 2001 3 -- 702 58 5 White-thin plume to ~100 m.
27 Feb-05 Mar 2001 -- -- 249 27 2 White-gray plumes to ~600 m.
06 Mar-12 Mar 2001 6 -- 303 31 -- --
12 Mar-18 Mar 2001 4 -- 349 10 3 --
19 Mar-23 Mar 2001 2 -- 259 -- 1 --
02 Apr-09 Apr 2001 28 -- 305 248 3 --
09 Apr-15 Apr 2001 -- -- 339 51 3 --
16 Apr-22 Apr 2001 -- -- 550 -- -- --
23 Apr-29 Apr 2001 12 1 759 157 4 --
30 Apr-06 May 2001 -- -- 782 96 7 --
07 May-13 May 2001 2 -- 670 113 7 --
14 May-20 May 2001 1 -- 616 143 2 --
28 May-03 Jun 2001 -- -- 396 115 3 --
04 Jun-10 Jun 2001 3 -- 430 75 5 --
11 Jun-17 Jun 2001 2 -- 361 81 4 --
18 Jun-24 Jun 2001 8 -- 346 62 3 --
25 Jun-01 Jul 2001 2 -- 331 37 2 --
02 Jul-08 Jul 2001 -- -- 299 30 6 --
09 Jul-15 Jul 2001 -- -- 687 57 11 --

During 27 March-1 April 2001, VSI personnel observed several lava avalanches that traveled to Kembar River valley as far as 750 m S of the summit. No seismic data were available because the seismometers broke on 24 March 2001. They were repaired on 1 April.

Geologic Background. Semeru, the highest volcano on Java, and one of its most active, lies at the southern end of a volcanic massif extending north to the Tengger caldera. The steep-sided volcano, also referred to as Mahameru (Great Mountain), rises above coastal plains to the south. Gunung Semeru was constructed south of the overlapping Ajek-ajek and Jambangan calderas. A line of lake-filled maars was constructed along a N-S trend cutting through the summit, and cinder cones and lava domes occupy the eastern and NE flanks. Summit topography is complicated by the shifting of craters from NW to SE. Frequent 19th and 20th century eruptions were dominated by small-to-moderate explosions from the summit crater, with occasional lava flows and larger explosive eruptions accompanied by pyroclastic flows that have reached the lower flanks of the volcano.

Information Contacts: Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/).